You are required to draw blood from a patient and to keep it in a test tube for analysis of blood corpuscles and plasma. You are also provided with the following four types of test tubes. Which of these will you not use for the purpose
Test tube containing calcium bicarbonate
Chilled test tube
Test tube containing heparin
Test tube containing sodium hydroxide
C.
Test tube containing heparin
Clotting of collected blood can be prevented by
1) coating test tubes with silicon (which produce non wettable surface similar in its smoothness to endothelial lining of blood vessels).
2) adding chelating agents (includes trisodium citrate, sodium oxalate and sodium EDTA) which remove calcium which is important for blood coagulation, and prevent blood clotting.
3) adding heparin, most powerful anticoagulant which acts indirectly by activating plasma antithrombin III. Heparin is effective both in vivo and in vitro. Whereas the option a, b and d are effective in vitro. Heparinized blood is not suitable for blood counts (as it alters the shape of RBC's and WBC's which affects blood testing), Fragility testing and complement fixation tests.
